Describe releases as SemVer git tags in the README (closes #226)

The first section of the README said the project had no versioned
release. It now says releases are git tags named by SemVer and names
the first one. That sentence opens the paragraph on where `mfer
version` gets its number, in place of its old opening sentence, "A
version is a git tag", which the new one covers. The rest of that
paragraph is unchanged and still matches `script/build`,
`script/docker` and the `Dockerfile`.

Model: opus-5-5

README.md

@@ -13,14 +13,11 @@ The structure of these files can be found
 schema `mfer/mf.proto` for exact field numbers and types. Both are included in
 the [project repository](https://git.eeqj.de/sneak/mfer).
 
-The current version is pre-1.0 and while the repo was published in 2022, there
-has not yet been any versioned release. [SemVer](https://semver.org) will be
-used for releases.
-
-A version is a git tag, and no file in the tree records a version number.
-`mfer version` prints the revision the build stamped into the binary, which for
-`make build` and the Docker image is the output of `git describe` on the
-checkout they build. A binary built without that stamp, as
+Releases are git tags named by [SemVer](https://semver.org), starting with
+`v1.0.0`. No file in the tree records a version number. `mfer version` prints
+the revision the build stamped into the binary, which for `make build` and the
+Docker image is the output of `git describe` on the checkout they build. A
+binary built without that stamp, as
 `go install sneak.berlin/go/mfer/cmd/mfer@<tag>` builds it, prints the module
 version Go records in it instead. A program that imports the `mfer` package
 finds the version it was built against in its own build information